High temperature slow electromagnetic device



Jan. 26, 1937. A. B. RYPINSKI HIGH TEMPERATURE SLOW ELECTROMAGNETIC DEVICE Filed Dec. 20, 1933 3 Sheets-Sheet 1 IN VEN TOR.

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BY 6 w AT'TORNEY 7 Patented Jan. 26, 1937 UNITED STATES PATENT OFFICE HIGH TEMPERATURE SLOW ELECTRO- MAGNETIC DEVICE 22 Claims.

trol systems and more particularly to a construction of high temperature slow electromagnetic device for use in electrical control systems.

In my copending applications and patents hereinafter enumerated, I have described electromagnetic devices which produce changes in magnetism over time periods to effect various results for numerous purposes. The list is as follows: Serial No. 416,877-filed Dec. 27, 1929, for Slow electromagnet; Serial No. 608,095-filed Apr. 28, 1932, for Slow reactor or circuit controller, now "Patent 1,972,112, dated September 4, 1934; Serial No. 671,767filed May 18, 1933, for Slow electromagnets having the same or similar temperature coefficients of resistance materials in differential windings. Serial No. 671,768-filed May 18, 1933, for Conductors for slow electromagnets and reactors, now Patent 1,972,319, dated September 4, 1934; S. N. 699,616-filed Nov. 24, 1933, for Motor starting systems; S. N. 699,617-filed Nov. 24, 1933, for Circuit control and current control system; S. N. 699,618-filed Nov. 24, 1933, for Motor control system; S. N. 699,619-filed Nov. 24, 1933, for Distribution system; S. N. 699,620filed Nov. 24, 1933, for Are welding apparatus; S. N. 705,4 66filed Jan. 5, 1934, for Slow electromagnetic devices having different temperature coeflicient of resistance materials in assistant windings; and Patent No. 1,884,877dated Oct. 5, 1932, (Division of application 416,877, filed Dec. 27, 1929), for Circuit controller.

In general, with the exception of the Circuit controller Patent 1,884,877, each of the foregoing applications employ a pair of windings induetively coupled and connected in parallel one with respect to the other. In some cases a resistor is placed in series with one or each of the two windings inside the parallel connection, the resistors supplying the temperature variable resistance element. In any case the change in magnetism of the coil as a whole results from changes in the net resultant magnetomotive force of the two paralleled and magnetically coupled windings, which changes result from variations in the relative ampere turns and amperes in the two paths. 'Variations in amperes result from changes in resistance with heating of the parallel windings or resistors connected therewith.

My present invention is directed to additional means for effecting th purposes described in the prior applications cited and for efi'ecting pur- (01. 171-119) My invention relates broadly to electrical conposes not disclosed in any prior case. In each instance the slow electromagnet device set forth herein will include the equivalent of two inductively coupled windings connected in parallel one with respect to the other. They may be formed of the same or different temperature coefiicient of resistance materials, but will always include in one or both windings, never in an external resistor, a part which will change in resistance with temperature. The tempera- 10 ture' coefl'lcients may be positive or negative, the turns of the two windings equal or unequal, the windings may be connected to assist one another or to oppose one another magnetically, all as fully disclosed in the cited art. 15

In electromagnetic devices as commonly constructed today the temperatures are kept at C. or below. In those embodying this invention where the heating takes place in some part or all of the electromagnetic windings, the physical problems surrounding the dissipation of the extra heat produced are important. This invention, is particularly directed to new means of solving heating problems and utilization of the new results obtained incidental thereto.

One of the objects of my invention is to produce a slow electromagnetic device which is capable of operation with at least one conductor red or white hot.

Another object of my invention is to produce a slow electromagnetic device wherein part or all of the windings operate at elevated temperatures in an evacuated or gas filled vessel.

Still another object of my invention is to produce a slow electromagnetic device wherein the 3 windings and magnetic core operate at elevated temperatures in an evacuated or gas filled vessel.

A further object of my invention is to produce a slow electromagnetic device wherein one part of each Winding is arranged for operation at elevated temperatures and the remaining part of each winding and the core operate at 50 C. or less, the high temperature windings having different temperature coefiicients of resistance and being mounted in an evacuated or gas filled vessel, with the low temperature windings and a the core outside the vessel.

A still further object of my invention is to produce a slow electromagnetic device wherein one 50 part of at least one winding is arranged for operation at red heat or above and is mounted in an evacuated or gas filled vessel, a second part of at least one winding is arranged for operation at 50 C. or less outside the vessel, and a third part of at least one winding is arranged for operation at temperatures above 50 C. but less than red hot and is outside of the vessel.

Another object of my invention is to produce a slow electromagnetic device wherein one winding is arranged for high temperature operation mounted in an evacuated or gas filled vessel and. the remaining winding and the core operate at 50 C. or less outside the vessel.

Another object of my invention is to produce a slow electromagnetic device wherein a part of one winding is arranged for operation red or white hot, mounted in an evacuated or gas filled vessel, while the remaining windings and the core are arranged for operation at 50 C. or less outside the vessel.

Still another object of my invention is to produce a slow electromagnetic device wherein a part or all of the windings operate at elevated temperatures in a glass tube.

A further object of my invention is to produce a slow electromagnetic device wherein part of the conductors comprising the windings are encased in a continuous glass tube with sufficient clearance between conductor and glass to allow ior expansion under heating.

A still furthe object of my invention is to produce a slow electromagnetic device in which part or all of the windings are arranged for operation at elevated temperatures and are molded in a glass or other high heat resisting material.

Another object of my invention is' to produce a slow electromagnetic device in which part of at least one winding is arranged for high temperature operation and is mounted in an air filled glass tube or vessel.

A further object of my invention is to produce a slow electromagnetic device in which part or all of the windings are arranged for operation at a red or white heat, the high temperature windings being mounted in an evacuated or gas filled vessel with transparent walls.

Still another object of my invention is to produce a slow electromagnetic device including at least one winding for operation at a red or white heat in a transparent walled evacuated or gas filled vessel to radiate light, heat and electromagnetic waves of varying intensity over a time cycle.

A urther object of my invention is to produce a slow electromagnetic device including at least one winding for operation at a red or white heat in a transparent walled evacuated or gas filled vessel for:

(1) Producing waves;

(2) Producing radiant heat;

(3) Producing light radiation;

(4) Moving a core, keeper, armature or rotating part;

(5) Altering the resistance, inductive reactance or power factor of the device.

(6) Inducing a voltage in a secondary winding; or

(7) Producing any combination of two or more of these effects in predetermined time sequence over a time period.

Another object of my invention is to produce a slow electromagnetic device in which, with constant total current, the energy losses are less when the windings are heated and producing magnetism than when cool and not producing magnetism, at least part of the windings of said device arranged for operation at elevated temperatures.

Still another object of my invention is to proradiating electromagnetic duce a slow electromagnetic device wherein one partof each winding is arranged for high temperature operation, and both high temperature parts are mounted in an evacuated or gas filled vessel, with one winding wound in spiral formation and insulated from the other, the hot windings having difierent temperature coefiicients of resistance and arranged in magnetic opposition.

A further object of my invention is to produce a slow electromagnetic device in which part or all of at least one winding is arranged to operate at elevated temperature mounted in an evacuated or gas filled vessel, and one winding is arranged to be open circuited, leaving the other energized.

Other and further objects of my invention will be understood from the specification hereinafter following by reference to the accompanying drawings, wherein:

' Figure 1 shows a partial section of an electromagnetic device embodying my invention in a lamp bulb; Fig. 2 is a side view partly in section; Fig. 3 is a sectional plan view on line 3--3 of Fig. 2, of a modification of Fig. l with both windings but not the core in an evacuated or gas filled vessel; Figs. 4, 5, 6, and 7 are modifications of my invention shown diagrammatically; Fig. 8 is a design of connections of the device shown in Fig. 7; Fig. 9 is a diagram showing a switch in circuit with one winding; Figs. 10 and 11 are further modifications shown diagrammatically; Fig. 12 indicates the method of supporting a spiral conductor; Figs. 13 and 14 are two views of the same device Fig. 14 including a diagram of light. heat and magnetic rays radiating to intercepting devices, Fig. 14 showing a vertical sectional view on line l4--|4 of Fig. 13.

In practising my invention, the greater difierence in temperature I can introduce from initial to final condition the more effective the device. Materials available for very high temperature operation include a number with low temperature coeificients of resistance which can be successfully operated in air at l000 C. Pure nickel has a high positive temperature coefficient of resistance and may be successfully operated in air up to approximately 1000 C. In incandescent lamps, however, tungsten is regularly operated at 2000 C. to 2400 C. and in the carbon lamp the filament is operated at a somewhat lower temperature. It will thus be seen that if conductors are mounted in evacuated or gas filled vessels as in this application they can be operated at considerably higher temperatures than those available for operation in air.

In my copending application No. 416,877, filed December 27, 1929, I show a tungsten lamp in series with one of the two paralleled windings and a carbon lamp in series with the other. In my Patent No. 1,884,877, dated October 25, 1932, a division of my application No. 416,877, I show both filaments in a single evacuated vessel. In my present invention, I enclose part or all of the windings of my electromagnetic device in an evacuated or gas filled vessel, ordinarily oi glass for small current capacities. This results in a self contained device the windings of which may be heated to temperatures well above those otherwise practicable.

Figure .1 illustrates such a device. A pair of toroidal windings l and 2 are arranged on a core 3 of magnetic material and supported by wires 4, 6 and 1 in an evacuated or gas filled bulb 5. The wire 5 also carries current from the screw shell into the core 3 to which are 7 grounded the ends I0 and H of the windings and 2. The other ends of windings 2 and I are joined to wire 1 at |2. Wire 1 connects with button 9 which is insulated from the screw shell by cement l3. The windings need not be grounded but may be connected directly with wire 6. Supporting means for the windings are not shown but the core 3 may be-heavily coated with glass or other refractory material and the conductors laid on or insulated-in any other manner. Comparing Fig. 1 with the external resistor types shown in my copending applications it will be seen that each part of the windings and 2 contributes to the magnetic action, whereas series resistors do not.

Figs. 2 and 3 show a modification wherein the windings l4 and I5, which correspond to windings and 2 in Fig. 1, are contained in an evacuated or gas filled vessel It of cylindrical or tubular shape having the center limb of a laminated core I! passing through the open center of the cylinder. This eliminates the problem of supporting the relatively heavy core within the vessel as was shown in Fig. 1. The terminals |8, H3, and 20 are brought out through the wall of the glass envelope I6 and the windings l4 and |5 are mounted on the inner wall of the glass vessel |6.

Fig. 4 shows two windings 2| and 22 mounted on the center limb of a core 23. The windings are connected in parallel and to the incoming and outgoing lines at points 24 and 25. Here only winding 22 is contained in the evacuated or gas filled vessel 26. Winding 2| is the usual type of low temperature winding. The high temperature is therefore confined to the Winding 22.

Fig. 5 shows a further modification where each of two windings 2| and 22 have in series a high temperature portion 2| and 22', the high temperature portions contained in a two compartment evacuated or gas filled vessel 21. The two low temperature portions 2| and 22 with their high temperature series portions'2l and 22 are connected in parallel and to the incoming and outgoing lines at 28 and 29. The core is shown at 30. The vessel 21 may be one piece with a dividing wall 21a as shown, or onepiece with no dividing wall, or there may be two separate vessols each containing one winding. The arrangement shown in Fig. 5 is highly efficient. Windings 2| and 22' are of few turns but change radically in resistance due to the high temperatures they attain. The windings 2| and 22, operating at low temperature, may have many turns to produce a high magnetization. The high temperature parts act as resistors and also assist in setting up magnetism in the core 30. Because of their few turns but little energy is required to heat them and their cooling time is correepondingly rapid. If the windings 2| and 22- are formed of materials with radically different temperature coefficients of resistance, as, for instance, tungsten and carbon, a device results in which the total resistance change is negligible or very small as compared with the change in magnetism and inductive reactance with heating. This is so because the increase in resistance of the tungsten is counterbalanced by the decrease in resistance of the carbon. The construction illustrated in Fig. 5, under certain conditions. may have a much longer time element than the construction shown in Fig. 4. The time element of the device is the heating time of the high temperature windings. If winding 22 in Fig. 4

is of tungsten, a large inrush of current will occur when it is energized due to the very low resistance cold of the tungsten. This heats the conductor very fast as compared with the Fig. 5 design where the windings 2| and 22 act as resistors to limit initial current surges.

Fig. 6 carries the segregation of the high temperature winding one step farther. Here 3| and 32 are low temperature windings and 32' is a h gh temperature winding forming with winding 32 a complete winding. 3| is connected in parallel with 32-'32 in series as shown. As illustrated in Fig. 6, winding 32' is mounted in an evacuated or gas filled vessel 33 and the windings and vessel supported on core 34. In this design the losses and heat problems are still further reduced. Leads 35 and 36 serve to connect the device in a circuit.

In all cases suitable supports for the conductors within the vessel are required, both to support the r weight and to reinforce them against magnetic forces to which they may be subjected in operation. These means of support have not been illustrated in the drawings in all cases as they form no essential part of my invention. I may utilize any of the suitable means of conductor support as commonly employed in incandescent lamps, electron discharge or X-ray tubes, or for heavy currents, as in large mercury rectifiers.

In Fig. 7 the two windings 4| and 42 are mounted on a core 43 having a movable armature 44, retractable by a spring 45. The connection of the wind ngs in parallel across a line 46 and 41 is indi cated diagrammatically in Fig. 8. Inthis case the high temperature winding 42 consists of a single turn or conductor 48 mounted in a tube 49 of glass or other refractory material. The tube may be evacuated or gas filled. If the temperatures encountered are not high enough to warrant a vacuum or inert gas for protection of.the

v conductor, or if the high temperature condition will be of short duration the tube shown in Fig. '7 may be air filled. In some cases it may be desirable to have it air filled and permit the conductor therein to burn out if the current is excessive or is continued high for too long a period of time.

In the operation of my electromagnetic device it is sometimes desirable to convert it from a slow to an instantaneous device, or'vice versa. I may include means to accomplish this in the form of a switch 49 in Fig. 9, in which lines 53 and 54 carry current into and out of windings 5|, 52 and 52'.

When the switch is opened the windings 52 and 4 52' carry the total current, and magnetism is increased or decreased practically instantaneously with current changes whereas while switch 49 is closed the device produces slow magnetism, depending on temperature changes in winding 52. The switch may be manually operated or operated by any well known thermostatic or remotely controlled devices.

If the high temperature winding is designed to fuse and burn out under certain cond tions as described in connection with Fig. 7 it will produce the same result as the switch in Fig. 9 and convert the device to an instantaneous type electromagnetic device.

Fig. 10 shows a further modification of the construction shown in Fig. '7. A transformer has as its primary wind'ng a low temperature winding 6| joined in parallel with a high temperature winding 62, across a supply line 68. The latter wind-- ing consists of a conductor 63 in a glass or other refractory material '64 which may be evacuated, gas or air filled. The secondary winding 65 supplies a load 66. The core is indicated at 61. The individual turns are here supported separately. The tube may be a fairly close fit over the conductor, allowing only for expansion.

Fig. 11 shows a construction of high temperature winding where the winding 12 is cast in glass or other suitable high temperature material or refractory. When cast in glass the conductors will be plainly visible, as the wires are visible in the well known wired window glass. Here II is a low temperature winding in parallel with winding I2 across lines I5 and 16. The core 13 has a movable armature I4 magnetically controlled. The casing for the various evacuated or gas filled vessels described may be of glass, porcelain, or if of metal as used for mercury rectifier tubes, have a water, mercury or other type seal. I do not limit myself to any particular construction of casing but may use any suitable material or design.

To illustrate mathematically the operation and advantages of the electromagnetic device oi my invention, assume a device constructed as in Fig. 6 wherein winding 3! has turns, winding 32 has 98 turns and 32' has two turns. The lines 35 and 36 are connected in series with adirect current line, not shown, in which a current of two amperes is maintained by means not shown. Assume no magnetic leakage between windings 3| and 32-32. Assume winding 3! has ten ohms resist ance, winding 32 eight ohms resistance, and winding 32' has two ohms resistance cold, and ten times as much or twenty ohms, when white hot. The net ampere turns for each condition will be as shown in the following table:

Cold condition Winding 3232 Winding 31 10 ohms 10 ohms.

l ampere l ampere. 100 turns 100 turns.

Total 100 mnpereturns lmampere-turns. Watt loss 1 R 10 watts 10 watts.

Net difference Zero Total losses 20 watts Hot condition Winding 3232 Winding 31 Resistance 28 ohms 10 ohms.

.526 amperes 1.474 amperes. 100 turns 100 turns.

Total 52.6 ampere- 147.4 ampereturns. turns. Watt loss 1 R 7.65 watts. 21.72 watts.

Net difference 94.8 ampere turns Total losses 29.37 watts It will be observed that winding 32-32 rose in resistance from 10 ohms to 28 ohms, almost three times as much. It is obviously more effihot turns, even though the 100 turns do not get white hot.

Assume a second case using the device shown in Fig. 5 where windings 2i and 22 each have ninety-eight turns and 2i and 22' each have two turns. Assume winding 2| of negative temperature coefficient of resistance material and 22' of positive temperature coefficient of resistance material. Assume winding 2| has four ohms resistance while winding II has six ohms cold and three ohms hot. Winding 22 has eight ohms resistance while winding 22 has two ohms cold and twenty ohms hot. The magnetic conditions, assuming no leakage, will then be as shown below:

Cold condition Winding 22-22 Winding 2l-2l' Resistance 10 ohms 10 ohms. Current l ampere l ampere. Times 100 turns 100 turns.

Total 100 ampere-turns 100 ampere-turns. Watt loss 1 R 10 watts 10 watts.

Net difference Zero ampere-turns Total losses 20 watts Hot condition Winding 22-22 Winding 21-21 Resistance 28 ohms 7 ohms. Current .4 ampere. 1.6 amperes. Times 100 turns 100 turns.

Total 40 nmpere-turns 160 ompereiums. Watt loss 1 R 4.48 watts. 17.92 watts.

Net difference ampere-turns Total losses 22.4 watts Using negative temperature coefficient of resistance material in two turns of winding 2| thus results in increasing the net ampere-turns from 94.8 to 120. An additional beneficial effect of using negative coefficient material is that the watts required to produce this extra number of ampere-turns difference are less than those required in the former case, i. e., 29.37 watts were used to produce 94.8 ampere-turns in the first example whereas only 22.4 watts were used to produce 120 ampere-turns in the second.

I may use a negative coeflicient material in winding 32', Fig. 6, and the watts required when hot will be less than when cold.

The foregoing illustrations will serve to show the desirability of those forms of my invention shown in Figs. 5, 6, and 9.

In my Patent 1,972,319, dated September 4, 1934, based on my application Serial No. 671,768 filed May 18, 1933, for Coil for slow electromagnets and reactors, I show the two conductors forming part of opposed windings as made up of an insulated inner conductor as part of one winding and an insulated outer conductor wrapped over the inner conductor in spiral formation and forming part of the other winding. I may employ this same opposition effect in the high temperature windings of Figs. 1, 2, 3, and 5, or in any low temperature windings. In the high temperature windings I may maintain the inner and outer conductors in spaced relationship one with respect to the other by glass castings at spaced intervals as shown in Fig. 12 where ii is the inner and 82 the outer conductor and 83-83 are the cast glass beads fixing the relationship of the conductors and preventing them from touching. Any other suitable means may be used for the same .purpose.

My invention lends itself to a. wide variety of uses. In general it may be utilized for any purpose where magnetism which increases, decreases or changes over a time cycle is required. Incidental to the production of high temperatures in the windings which generate the magnetism, my invention may be utilized to produce radiant heat, light or radiant electromagnetic waves through the medium 'of its transparent glass or other material casing, and the time cycle over which these effects are produced may correspond to a predetermined time cycle in the increase or decrease in magnetism. The electromagnetic properties may be used for any of the purposes disclosed in my copending applications cited herein. When the device includes at least one winding for operation at a red or white heat in a transparent walled evacuated or gas filled vessel the device may be used for:

(1) P r o d u c in g radiating electromagnetic waves;

(2) Producing radiant heat;

(3) Producing light radiation;

(4) Moving a core, keeper, armature or rotating part;

(5) Altering the resistance, inductive reactance or power factor of the device;

(6) Inducing a voltage in a secondary winding; or

(7) Producing any combination of two or more of these eifects in predetermined time sequence over a time period.

The time sequences in which these effects occur may be varied at will over a wide range. For example, the maximum magnetism may be present when the windings are in their initial cold condition, in which case there would be no light or heat. After the windings heat and are giving oif light, the magnetism can disappear; or the reverse can be the case, the light, heat, and mak-' netism reaching a maximum together; or the magnetism can start high, with no light or heat, reach zero at an intermediate point with a dim light and moderate heat, and rise again as the light andheat rise to full intensity.

Figs. 13 and 14 give two views of an electromagnetic device employing a high temperature winding and two low temperature windings, the former mounted in an evacuated or gas filled vessel to produce simultaneously or in sequence all the various effects just outlined. In Fig. 13 is shown a core 90 of magnetic material having mounted on it a winding 9| connected in series with a supply line H8 and a load III. In parallel with winding 9| there is connected a series circuit made up of a second winding 92 and a high temperature winding 92'. Winding 92' consists of several turns of conductor 95 mounted on supports 93 within an evacuated or gas filled vessel 94. e The. method of supporting conductor 95 is indicated conventionally and may take any suitable form. A lead-in conductor 96 is joined at 9-1 to the supply line. Lead-out conductor I02 is connected at I03 to winding 92, the other terminal I04 of which is connected at I05 to the load circuit. This forms the main or primary circuit through the device in parallel with winding 9|. The core 90 is arrangedto have two magnetic paths. There is a closed magnetic circuit through the center limb I06, end limbs I01 and I08, and limb I09. Mounted on limb I09 is a third winding acting as the secondary of. a

' direct current as with the others.

The second magnetic path forming part of core 90 embraces center limb I06 and end limbs H3. The ends 'of limbs us are shaped at H4 to'provide clearance and suitable air gaps to' permit 'a rotating armature I I5, turning on pivot I I 6, to pass. The armature H5 is shown as a cam shaped structure of magnetic material whose shape biases it to rotate clockwise when there is sufficient magnetism at poles II4. This is a conventions. Illustration of a pivoted, rotating or movable structure to be set in motion by magnetism originating in the electromagnetic device, and may be an armature of a motor of any well known type, a sliding core, a pivoted or sliding armature or any other well known construction for translating magnetic action into mechanical work. Electrically the main winding 9|, 92 and 92' of the device function to alter the total resistance, inductive reactance and/or power factor of the device, also the magnetism in core 90, all of which efiects occur over a time cycle determined by the heating of the windings and their differential changes in resistance as thoroughly explained herein and in the copending patent applications mentioned herein.

If the device is connected in series with a supply sourceand a load as shown at II'I, it may be used to affect the voltage, current and/or power factor of the load circuit. If the device is connected directly across the supply line 8 it may be used electrically to alter the total inductive reactance, resistance and/or power factor of the load connected to said power line over a time cycle. The supply may be direct current, alternating current, pulsating or any other combination. Since its primary functioning is the result of changes in heating of conductors it will function regardless of the type of current supply. On direct current there will be no inductive effects except when the current or magnetism are changing fairly rapidly but otherwise the device wiil function as described on If on alternating current the device may be made up for use on polyphase currents in ways well understood by those skilled in the art. For simplicity it has been shown for single phase operation.

In Fig. 14 is shown a sectional view on line |4| of the device described in Fig. 13. The purpose of Fig. 14 is to show conventionally the method of utilization of three additional effects obtainable from the same device simultaneously or in time sequence to the effects just described. In Fig. 14 the core 90 carries windings 9|, 92 and 92. If the windings 92' are heated sufficiently, heat begins to be radiated therefrom. The glass structure 94 permits these heat rays to pass freely as indicated at 9. If a device I20 is interposed in the path of the rays and the device is sensitive to and effected by said rays, they may be utilized to operate said device over a time cycle determined by the time cycle of heating of winding 92. The heat sensitive device may be a thermometer, a thermostatic device or any other suitable well known apparatus. As heating of winding 92 continues a point is reached at which winding 92' passes to a red, and if continued to a white heat.

Light is now radiated as indicated at I 2| and a device I22 sensitive to and operated by light L rays may be interposed in these rays to be operated over a time cycle, corresponding to the heating time cycle of winding 92'. This device may be any well known light sensitive cell such as the selenium cell or devices used in the electric eye" or the photronic cell or photocell.

The electromagnetic waves generated by the device as a whole, and winding 92' in particular, may radiate as indicated at I23 and be picked up by a device I24 sensitive to such waves to produce a signal or other result dependent on the intensity of the radiation over a time cycle. Apparatus I24 may be a radio receiving set or any other suitable appliance.

While I have described a number of preferred embodiments of my invention, I do not intend to limit myself to the exact constructions herein disclosed except insofar as defined by the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. An electromagnetic device comprising two windings connected in parallel one with respect to the other, effectively coupled magnetically for mutual induction and arranged, when energized, to produce changes in magnetism by means of disproportionate changes in resistance with temperature of the two windings thereof, and a gas filled vessel enclosing the elevated temperature windings.

2. An electromagnetic device as in claim 1, except that one complete winding is arranged for operation at temperatures above a red heat.

3. An electromagetic device as in claim 1 except that part of each winding is arranged for operation at temperatures above a red heat.

4. An electromagnetic device as in claim 1 except that both windings are arranged for operation at temperatures above a red heat.

5. An electromagnetic device comprising two windings connected in parallel one with respect to the other, said windings being eifectively coupled magnetically for mutual induction, means to energize said' windings, at least part of one winding being arranged for operation at elevated temperatures, an evacuated vessel containing said high temperature winding, supporting means for said high temperature winding within said vessel, said windings proportioned to produce changes in magnetism by means of disproportionate changes in resistance with temperature of the two windings thereof.

6. An electromagnetic device as in claim 5 except that the two inductively coupled windings are arranged for operation at elevated temperatures, and are mounted on a core of magnetic material, said windings being contained in an evacuated vessel.

7. An electromagnetic device as in claim 5 except that one of the two inductively coupled windings. is arranged for operation at elevated temperatures, both of said windings being mounted on a core of magnetic material, said high temperature winding being mounted in an evacuated vessel with the other winding and core adiacent said vessel.

8. An electromagnetic device as in claim 5 wherein said evacuated vessel is formed of glass.

9. An electromagnetic device as in claim 5 wherein said evacuated vessel is formed of material capable of transmitting light.

10. An electromagnetic device as in claim 5 wherein the high temperature winding within the evacuated vessel radiates heatfrom its high temperature surfaces through the medium of walls of said vessel, said walls being formed of material capable of transmitting radiant heat.

11. An electromagnetic device as in claim 5 wherein the high temperature winding within the evacuated vessel radiates light from its high temperature surfaces through the walls of said vessel, said walls being iormed of material capable of transmitting radiant light.

12. An electromagnetic device as in claim 5 including switching means to interrupt the circuit through one of the paralleled windings leaving the second winding in the circuit and energized.

13. An electromagnetic device as in claim 5 wherein part of each of the inductively coupled windings is arranged for high temperature operation within an evacuated or gas filled vessel, one of said high temperature windings being formed of positive temperature coefiicient of resistance material and the other of said high temperature windings being formed of negative temperature coeflicient of resistance material.

14. An electromagnetic device as in claim 5, except that all of said windings are mounted on a core of magnetic material and a portion only of one of said windings is arranged for high temperature operation in an evacuated vessel.

15. An electromagnetic device comprising two windings connected in parallel one with respect to the other, said windin s bein effectively coupled magnetically for mutual induction therebetween, means to energize said windings, at

least part of one winding being arranged for operation at elevated temperatures, a vessel containing said high temperature winding, said vessel supporting said winding within said vessel and formed of material capable of transmitting light, said windings proportioned to produce changes in magnetism by means of disproportionate changes in resistance with temperature 1 of the two windings thereof.

16. An electromagnetic device comprising two windings connected in parallel one with respect to the other, said windings being effectively coupled magnetically for mutual induction therebetween', means to energize said windings, at least part of one winding being arranged for operation at elevated temperatures, a vessel containing said high temperature winding, said vessel supporting said winding within said vessel, said windings proportioned to produce changes in magnetism by means. of disproportionate changes in resistance with temperature of the two windings thereof.

17. An electromagnetic device as in claim 5 wherein the high temperature winding within the evacuated vessel radiates electromagnetic waves from its high temperature surfaces through the medium of its walls, said walls being formed of material capable of transmitting radiant electromagnetic waves.

18. An electromagnetic device as in claim 5 wherein the high temperature winding within the evacuated vessel radiates heat and light from its high temperature surfaces through the medium of its walls, said walls being formed of material capable of transmitting radiant heat and light.

19. An electromagnetic device as in claim 5 wherein the high temperature winding within the evacuated vessel radiates heat, light and electromagnetic wave: from its high temperature surfaces through the medium of its walls, said walls being ioimed of maieri l capable of transmitting radiant heat, light and electromagnetic waves.

20. An electromagneticidevice as in claim 5 wherein the high temperature winding within the evacuated vessel radiates heat and electromagnetic waves from its high temperature surfaces through the medium of its walls, said walls being formed of material capable of transmitting radiant heat and electromagnetic waves.

21. An electromagnetic device as in claim 5 wherein the high temperature winding within the evacuated vessel radiates light and electromagnetic waves from its high temperature surfaces through the medium of its walls, said walls being formed of material capable of transmitting radiant light and electromagnetic waves.

22. An electromagnetic device as in claim 5 except that one of the two inductively coupled windings is arranged for operation at elevated temperatures, both of said windings being mounted on a core of magnetic material where said core has a movable portion.

ALBERT B. RYPINSKI. 

